Yes, I’ve done it too. Always with the best of intentions. Here’s a sample of my internal monologue: “Gosh, that looks like an interesting headline. I’ll retweet it… [Click!] And now to go read the po-… Hey! Liza Donnelly just posted another cartoon!”
You may have noticed this happening with your own posts (in which case, I swear I’ll get around to reading them). If you’re using an URL-shortener like bit.ly, you can track statistics… and from time to time, you’ll see the number of retweets substantially outstrip the number of clickthroughs.
I haven’t done any real study of the issue (to some lucky doctoral student reading this: you’ve just found the topic for your thesis) but I have a few guesses about underlying causes: distraction, a headline that seems to say it all, posts that people don’t want to read themselves but figure would be good for their users. (This is how I feel about eating vegan.) And maybe I just write better tweets than blog posts.